Reference method javascript

JavaScript reference method

JavaScript is a scripting language widely used in Web development and the most common programming language. What is different from other programming languages ​​is that JavaScript can implement different reference methods in its syntax and rules to achieve different functions.

There are four main ways to reference JavaScript. Each of these methods has its own uniqueness and scope of application. They will be introduced to you respectively below.

1. Global reference

Global reference refers to inserting JavaScript code into the head of the document and can be referenced throughout the page. This reference method is suitable for script code that needs to be used in different pages or needs to be run globally.

For example:

<script type="text/javascript" src="yourScript.js"></script>

The JavaScript files referenced in this way will be effective in the entire HTML document and can be used to define global variables, global functions and other functions.

2. Internal quotation

Internal quotation refers to embedding JavaScript code into the HTML document, usually in the script tag of the head or body. This reference method is suitable for situations where the document needs to be modified or processed using JavaScript.

For example:

<script type="text/javascript">
  console.log("Hello, World!");
</script>

This reference method is simple and easy to modify and maintain. However, for large projects or projects with multiple HTML pages, this reference method couples the code together, which is not conducive to Code reuse and management.

3. External link reference

External link reference means storing JavaScript code in separate .js files, and then referencing these files through the script tag of the HTML document. This reference method is suitable for when you need to use the same script code multiple times, or when you need to use third-party libraries, frameworks, etc.

For example:

<script type="text/javascript" src="yourScript.js"></script>

This reference method can improve the maintainability and reusability of the code, and facilitate unified management and modification of JavaScript code.

4. Modular reference

Modular reference refers to using modular standards to define and organize JavaScript code to achieve modular code writing and split the code into separate logic module to achieve full functionality. This method is suitable for large projects or collaborative development by multiple people. Modularization allows each developer to focus on his or her own part, and unitize development in the entire project, reducing the coupling of the code and improving the maintainability of the code.

For example:

import { getYear, getMonth, getDate } from './myDate.js';
console.log(getYear() + "-" + getMonth() + "-" + getDate());

This reference method also requires the use of modular frameworks or libraries, such as CommonJS, AMD, RequireJS, etc.

Summary

The above are the four commonly used reference methods in JavaScript, which are suitable for different application scenarios and project needs. Developers should choose the appropriate reference method based on actual project conditions to achieve efficient development and code maintenance.

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